USGS - science for a changing world

Open File Report 2007–1142

Log ASCII Standard (LAS) files for geophysical wireline well logs and their application to geologic cross sections through the central Appalachian basin

By Robert D. Crangle, Jr.

Sample PDF page.

PDF (704KB, 14 pages)

Introduction

The U.S. Geological Survey (USGS) uses geophysical wireline well logs for a variety of purposes, including stratigraphic correlation (Hettinger, 2001, Ryder, 2002), petroleum reservoir analyses (Nelson and Bird, 2005), aquifer studies (Balch, 1988), and synthetic seismic profiles (Kulander and Ryder, 2005). Commonly, well logs are easier to visualize, manipulate, and interpret when available in a digital format.

In recent geologic cross sections E–E' and D–D', constructed through the central Appalachian basin (Ryder, Swezey, and others, in press; Ryder, Crangle, and others, in press), gamma ray well log traces and lithologic logs were used to correlate key stratigraphic intervals (Fig. 1). The stratigraphy and structure of the cross sections are illustrated through the use of graphical software applications (e.g., Adobe Illustrator). The gamma ray traces were digitized in Neuralog (proprietary software) from paper well logs and converted to a Log ASCII Standard (LAS) format. Once converted, the LAS files were transformed to images through an LAS–reader application (e.g., GeoGraphix Prizm) and then overlain in positions adjacent to well locations, used for stratigraphic control, on each cross section.

This report summarizes the procedures used to convert paper logs to a digital LAS format using a third–party software application, Neuralog. Included in this report are LAS files for sixteen wells used in geologic cross section E–E' (Table 1) and thirteen wells used in geologic cross section D–D' (Table 2).


Contents

LAS Files

All LAS files.zip (3,916KB)
Table 1 D-D' LAS files.zip (1,828KB)
Table 2 E-E'LAS files.zip (2,086KB)


This document is available online only in Portable Document Format (PDF); the latest version of Adobe Acrobat Reader or similar software is required to view it. Download the latest version of Acrobat Reader, free of charge or go to access.adobe.com for free tools that allow visually impaired users to read PDF files.

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov  logo U.S. Department of the Interior | U.S. Geological Survey
URL:http://pubsdata.usgs.gov/pubs/of/2007/1142/index.html
Page Contact Information: Web team
Page Last Modified:Friday, 11-Jan-2013 04:44:55 EST